A substantial proportion of old people in this country have dietary intakes of protein, calories, vitamins, and iron that are below the recommended dietary allowances. It is not known, however, what effect this "subclinical" malnutrition in old people has on their physical health and life expectancy. In this proposal we will follow 250 healthy old people over a five year period. The nutritional status of these subjects will be evaluated yearly by clinical exam, a three day dietary record, and biochemical analysis of blood samples for total protein, albumin, transferrin, serum iron and iron binding capacity, vitamins A, C, B12, riboflavin, thiamine, pyridoxine, folic acid, copper, zinc, cholesterol, and HDL-cholesterol. We will then examine whether deficiencies of these nutrients as measured by dietary records and by biochemical analysis predisposes subjects to increased morbidity and mortality during the five year follow-up period. These healthy old people will also be evaluated immunologically with skin tests, and in vitro mitogen responses. We will examine whether subclinical malnutrition results in depressed immune function. The other major aspect of this study will be to prospectively study the impact of major life crises on the nutrition of our subjects. We will study the effects of hospitalization, change in living conditions, and bereavement on the dietary intakes of these subjects. We will determine which life crises cause a drop in dietary intake and how long dietary intake stays down. We will also psychologically test these subjects after the "life crises" to determine the relationship between depression and nutritional status.